I have a 4000/60

I found on the netbsd web pages a page about performances of VAXen

there is written speed factor 12 and compared to the 4000/90 which is 32

is it possible that 4000/90 is really twice faster than 4000/60 ??
anyway how to  compare this (unknown scale) speed factor to something
resembling SPECint95 ???

THen I Also read that on 4000/60 can be mounted up to 104MB RAM.
Where I Can find , I mean buy the SIMM modules for 4000/60 ??

thanks

rj45